1. Field of the Invention
The present invention generally relates to detecting contamination in lubricating oil. More specifically, the present invention relates to active filtering of oil in order to detect contamination that might otherwise result in catastrophic failure of engine or other moving parts.
2. Description of the Related Art
Contamination in crankcase oil decreases the lubricating ability of oil and will lead to engine failure. If a fuel injector becomes stuck in the open position, the introduction of large amounts of fuel in crankcase oil will decrease the viscosity of the oil. If the fuel contamination goes undetected, the decrease in viscosity will cause a loss of hydrodynamic lubrication resulting in metal to metal contact and ultimately causing spun and/or seized bearings.
Current methods for fuel detection include absorption spectroscopy, viscosity, and the use of a ‘sniffer’ to measure the aromatics in the gas above the oil.
Fuel contamination can be detected using absorbance spectroscopy, but the method has been developed for bench top measurements after a sample of oil has been removed from the crankcase.
Alternatively, and in the absence of other contaminants in the oil or chemical changes to the oil, fuel (in large enough quantities) can be detected by measuring the viscosity of the oil by comparing to the original oil viscosity. However, oil wear, water contamination, and soot contamination all cause an increase the viscosity of the oil making the specific detection of fuel contamination in oil by measuring its viscosity difficult.
A sniffer requires constant calibration with a known fuel/oil mixture which is impractical in an in-situ device. Still further, fuel does not significantly change other measurable qualities of the oil (conductivity, dielectric constant, resistance, capacitance, polarity, TAN, TBN etc) so a direct in-situ electrical or chemical measurement of the oil to detect the presence of fuel is difficult.
All of the foregoing methodologies are not suitable to ‘on the fly’ or ‘real time’ detection. A solution is needed that provides real-time feedback so that a system may determine the presence of contaminates that need to be removed from the oil and/or the need to introduce additive packages to the oil being monitored.